Chapter 8.2, Problem 1PE

(a)

Interpretation Introduction

Interpretation: To write ground–state electronic configuration of the element having 20 electrons.

Concept Introduction:

Electron configuration is the distribution of electrons in the atomic orbitals. It gives an idea about the shape and energy of electrons in an atom.

There are 3 rules to decide the electronic configuration of an atom. They are,

• Pauli Exclusion Principle: No two electrons should not have same four quantum numbers in an atoms that is, no two electrons should have same principal quantum number (n), same orbital angular momentum quantum number (l), the same magnetic quantum number ${\text{(m}}_{\text{l}}\text{)}$ or same spin magnetic quantum numbers ${\text{(m}}_{\text{s}}\text{)}$
• Aufbau Principle: In an atom, electrons fill according to the increasing energy of the orbital.
• Hund's Rule: The orbital having maximum number of electrons with same spin in separate orbitals is the most stable arrangement in an orbital.

(b)

Interpretation Introduction

Interpretation: To classify the element that has 20 electrons.

Concept Introduction:

• Electron configuration is the distribution of electrons in the atomic orbitals. It gives an idea about the shape and energy of electrons in an atom.
• The elements with same valence electrons have similar properties and are placed in the same group in periodic table.
• Group II in the periodic table contains 2 valence electrons.
• The outer electronic configuration of alkaline earth metals is ${\text{ns}}^{\text{2}}$.

(c)

Interpretation Introduction

Interpretation: To determine whether the element having 20 electrons is diamagnetic or paramagnetic.

Concept Introduction:

• Electron configuration is the distribution of electrons in the atomic orbitals. It gives an idea about the shape and energy of electrons in an atom.
• Paramagnetic compound contains at least one unpaired electron.
• Diamagnetic compound does not contain any unpaired electron